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Ac Hysteresis Loop Depending on the Phase Angle of the Higher Harmonic Induction
Derac Son,Eun Kyung Kim 한국자기학회 1996 Journal of Magnetics Vol.1 No.2
For the design of high efficiency electric machines, analysis of higher harmonic frequency components of the magnetic induction is necessary. We have measured ac magnetic properties of non-oriented silicon steel under harmonic frequencies ranging from 3rd (180㎐) to 9th (540㎐) and harmonic amplitude components from 10% to 50% of the total amplitude (Bmax = 1.5 T). From the experiment, it is found that, if the magnetic induction waveform has above 9th harmonic frequency components of the magnetic induction, the core losses only depended on the harmonic amplitude component, but if harmonic frequency becomes lower than 9th harmonic frequency, the core losses depend on the phase angle and the harmonic amplitude, and phase angle should be considered in the design of electric machine.
Prediction of Core Loss Including Higher Harmonic Inductions Using Two Symmetrical AC Minor Loops
Derac Son 한국자기학회 2003 Journal of Magnetics Vol.8 No.2
For the induction motor and inverter type motor design, prediction and analysis of core loss including higher harmonics have been studied. In this work, we have generated two symmetrical ac minor loop in the fundamental hysteresis loop whose positions are zero induction region and saturation induction region, and we could predict core loss including higher harmonics inductions. using the following modified superposition principle; Pc(B。, f。, Bh, nf。)=Pc(B。, f。)+(n-1)[k₁(B。)P_(cL)(Bh, nf。)+(1-k₁(B。))P_(cH)(Bh, nf。)].<br/> Using this equation we could also analyze core losses including higher harmonic induction under different maximum magnetic induction, different amplitude of higher harmonic induction with different harmonic frequencies.
Development of Magnetic Phase Detection Sensor for the Steam Generator Tube in Nuclear Power Plants
Derac Son,Won Ik Joung,Duck-Gun Park,Kwon Sang Ryu 한국자기학회 2009 Journal of Magnetics Vol.14 No.2
A new eddy current testing probe was developed to separate the eddy current signal distortion caused by permeability variation clusters and ordinary defects created in steam generator tubes. Signal processing circuits were inserted into the probe to increase the signal-to-noise ratio and allow digital signal transmission. The new probe could measure and separate the magnetic phases created in the steam generator tubes in the operating environment of a nuclear power plant. Furthermore, the new eddy current testing probe can measure the defects in steam generator tubes as rapidly as a bobbin probe with enhanced testing speed and reliability of defect detection.
Magnetic Sensor for the Defect Detection of Steam Generator Tube With Outside Ferrite Sludge
Derac Son,Wonik Jung,Duck Gun Park,Kwon Sang Ryu IEEE 2009 IEEE transactions on magnetics Vol.45 No.6
<P>Steam generator tube in nuclear power plant is a boundary between primary side and secondary side. Nondestructive test for the steam generator tube, eddy current testing (ECT) method has been carried out. In case of bobbin-type ECT probe, transverse defect, defect with ferro-phase, outside of tube having ferrite sludge were very difficult to detect. To overcome these problems, a motorized rotating probe coil (MRPC) probe was developed but scan speed is slow and not effective method in time. In this work we have developed a new sensor having U-shape of yoke to measure permeability variation of test specimen, which can detect ferro-phase generated as well as normal defects in the tube material of Inconel 6oo. Electronics for signal processing, 2-phase lock-in amplifier per sensor, ADC, and embedded controller were employed in one probe and measured digital data were transmitted to the PC data acquisition software using RS232C interface. Using the developed sensors we have applied to detect defects in the tube outside with ferrite sludge which is very difficult to detect conventional bobbin-type ECT probe. Developed sensor could measure defect size of 0.2 mm times 10 mm times 0.44 mm (width times length times depth) for the normal defect and defect outside of tube having ferrite sludge. We expect the developed sensor could detect defects like as MRPC probe and scan sensor speed like as bobbin-type ECT probe.</P>
Under Water Sonar Transducer Using Terfenol - D Magnetostrictive Material
Derac Son,Yuk Cho 한국자기학회 1999 Journal of Magnetics Vol.4 No.3
In this work we have constructed an under water sonar transducer using Terfenol-D rod employing open magnetic circuit. Normally Sonar transducer using Terfenol-D was designed under closed magnetic flux return path, and permanent magnet for dc bias marnetic field, but high magnetic field should be applied to the transducer coil for high sound power and it brings temperature increase inside of the transducer. To improve this heat dissipation problem, we have designed an open magnetic circuit type transducer and we can get 200 dB (re. 1 μPa @ 1m) sound power for the input power of 650 VA.
자기장크기 측정이 가능한 3-축 Flux-gate 마그네토미터 제작
손대락(Derac Son) 한국자기학회 2019 韓國磁氣學會誌 Vol.29 No.5
Magnetic field measurement under vibration and rotation condition of the magnetometer, total field measuring magnetometers have been used, because orthogonality error and scale factor differene of the 3-axis magnetometer can not measure total magnetic field with high precission. In this study, we developed total magnetic field sensor by orthogonality correction for the 3-axis flux-gate magnetometer. To correct orthogonality and scale factor, 24 bit 3-channel simultaneous digitizing ADC and DSP were used. To demonstrate the performance of the developed magnetometer under condition of vibration, the magnetometer was installed on dron and measured magnetic anormality of passenger cars. We can measure total magnetic field with resolution of 1 nT for the developed orthogonality corrected 3-axis flux-gate magnetometer.